My Home Inspector Blog: Sewer Gas Intrusion- Temecula Home Inspection

Sewer Gas Intrusion- Temecula Home Inspection

Sewer Gas Intrusion- Temecula Home Inspection

Plumbing vent at Temecula home inspectionJust yesterday, at a Temecula home inspection, I came across a situation I, unfortunately, have seen before. I was inspecting the attic area in a ten-year-old Temecula, CA home. The attic access was in the laundry room. As I entered the attic area, I could see the plumbing vent for the laundry drain system. There was a cut-out area over the attic access opening which opened into the attic space over the garage. When I viewed this area, I discovered that the plumbing vent terminated inside the attic! Sewer gases escaping into an attic area presents a serious health hazard for the occupants.


Apparently, the builder's plumber had overlooked this particular vent. It should have been extended through the roof. It's amazing that in a 10-year-old home this issue had not been discovered yet! Here are a couple more improperly-terminated plumbing vents I have come across in my travels:












In modern plumbing, a drain-waste-vent system (or DWV) removes sewage and greywater from a building and vents the gases produced by that waste. Waste is produced at the various fixtures (toilets, sinks, showers) and exits the fixtures through a trap, a dipped section of pipe that always holds water.







All fixtures must contain traps to prevent gases from backing up into the house. Through traps, all fixtures are connected to waste lines, which in turn take the waste to a soil stack, or soil vent pipe, which extends from the building drain at its lowest point up to and out of the roof. Waste is removed from the building through the building drain and taken to a sewage line, which leads to a septic system or a public sewer.


The venting system, or plumbing vents, consists of pipes leading from waste pipes to the outdoors, usually through the roof. Vents provide a means to release sewer gases outside instead of inside the house. Vents also admit oxygen to the waste system to allow aerobic sewage digestion. Vents provide a way to equalize the pressure on both sides of trap, thereby allowing the trap to hold water, which is needed to maintain effectiveness of the trap.


Every fixture is required to have an internal or external trap. Something I often see at home inspections are double traps or "S" traps. These incorrectly-configured traps are prohibited by the plumbing code.


First Choice Inspections is a Temecula home inspection company owned and operated by Steve Stenros, a CREIA certified inspector with the MCI designation (Master CREIA Inspector). Steve can be reached for appointment at 888-335-3040.



             Steve Stenros, MCI         Biz card photo

             Master CREIA Inspector #0115

             ICC Residential Combination Inspector #5251439

             Certified Infrared Thermographer #7791

                                       FHA/HUD Inspector- #V975

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Comment balloon 2 commentsSteve Stenros • May 06 2011 07:01PM


Steve, a very well explained post about a drain waste vent system.

Posted by Connie Harvey, Realtor - Nashville TN Real Estate (Pilkerton Realtors) over 9 years ago

Thanks, Connie. I'm always asked, "Why didn't the city inspector catch that?" Answer: They usually have such a huge work load each day, a lot of things get over-looked.

Posted by Steve Stenros, CREIA MCI, ICC, ACI Home Inspector,San Diego (Poway,La Jolla,Del Mar,Mira Mesa,Carlsbad,Escondido,Temecula) over 9 years ago